a(n) = A000043(n) - 3.

Terms

a(0) =0a(1) =2a(2) =4a(3) =10a(4) =14a(5) =16a(6) =28a(7) =58a(8) =86a(9) =104a(10) =124a(11) =518a(12) =604a(13) =1276a(14) =2200a(15) =2278a(16) =3214a(17) =4250a(18) =4420a(19) =9686a(20) =9938a(21) =11210a(22) =19934a(23) =21698a(24) =23206a(25) =44494a(26) =86240a(27) =110500a(28) =132046a(29) =216088